1. Field of the Invention
The present invention relates to a method of manufacturing a piezoelectric/electrostrictive film type device. More particularly, the present invention relates to a method of manufacturing a piezoelectric/electrostrictive film type device, in which the piezoelectric/electrostrictive film type device having a high resonance frequency can be manufactured with good efficiency while securing the conduction of each electrode.
2. Description of the Related Art
In recent years, piezoelectric/electrostrictive film type devices have been used in various applications such as a displacement control device, solid device motor, ink jet head, relay, switch, shutter, pump, optical modulation device, and fin. The film type device can control a minute displacement and has superior properties such as a high electromechanical transduction efficiency, high-speed response, high durability, and low power consumption. In recent years, however, in certain applications such as with an ink jet head, there has been a demand for a device having a higher speed response in view of the demand for the enhancement of printing quality and speed.
Additionally, piezoelectric/electrostrictive film type devices are generally produced by stacking a lower electrode, piezoelectric/electrostrictive layer, and an upper electrode in order on a substrate of a ceramic. However, in order to secure insulation between the electrodes while avoiding dielectric breakdown of the piezoelectric/electrostrictive layer, as shown in FIG. 15, a piezoelectric/electrostrictive film type device 30 has been developed including a piezoelectric/electrostrictive layer 73 disposed in such a size that an upper surface of a lower electrode 77 is coated and an end of the layer projects onto a substrate 44 (See JP-A-6-260694).
Moreover, in the conventional piezoelectric/electrostrictive film type device 30, a discontinuous plane is formed between a projecting portion 79 of the piezoelectric/electrostrictive layer 73 and the substrate 44. This is sometimes a cause for disconnection of the upper electrode 75. Therefore, it has also been described that a gap between the projecting portion 79 of the piezoelectric/electrostrictive layer 73 and the substrate 44 is filled with a predetermined resin layer (See said laid-open publication).
Needless to say, the piezoelectric/electrostrictive film type devices in which the resin layer is to be disposed, is very tiny, and it is difficult to coat only a predetermined portion with the resin layer. Therefore, the whole electrode has been coated with the resin layer under the present situation.
However, a large number of piezoelectric/electrostrictive film type devices are usually used in alignment and are electrically connected to one another. Therefore, it is quite important to manufacture the elelectrodes of each device so that the electrodes can be connected to another device or external connecting means, in order to manufacture final products having good efficiency. However, no consideration has been paid to this point in manufacturing the above-described piezoelectric/electrostrictive film type device. Therefore, an operation to remove a part of the resin layer formed on each electrode after forming the resin layer has been required. Additionally, damage such as cracks are generated in the resin layer that remains during the removing step. Furthermore, parts of the removed resin layer remain as particles in each portion of the device, which sometimes causes trouble with incomplete contact during the electric property inspection.
Moreover, in conventional piezoelectric/electrostrictive devices, based on the recognition that flexural displacement or generating force is adversely influenced by the connection between the projecting portion of the piezoelectric/electrostrictive layer and the substrate, an increase in the rigidity of the device has not been considered. Therefore, the recent demand to achieve a higher response speed has not necessarily been sufficiently satisfied.